Nothing heightens the tension in a science fiction movie more than watching the good guys’ spaceship get caught in an invisible tractor beam that slowly engulfs the villains. But what was once just a sci-fi staple could soon become a reality.
Scientists are developing a real-life tractor beam called an electrostatic tractor. However, this tractor beam cannot suck in the helpless spaceship pilot. Instead, it would use electrostatic gravity to safely expel dangerous space junk from Earth’s orbit.
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The science is pretty advanced, but the funding isn’t there yet.
Electrostatic tractor beams could alleviate that problem by safely moving dead satellites far outside Earth’s orbit, where they can drift harmlessly forever.
Although tractor beams won’t completely solve the space debris problem, the concept has several advantages over other proposed space debris removal methods and could be a valuable tool to tackle the problem, experts told Live Science.
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Prototypes can cost millions of dollars, and working full-size versions can cost even more. But if financial hurdles can be overcome, the tractor beam could be operational within 10 years, builders say.
“The science is pretty advanced, but the funding isn’t there yet,” project researcher Kaylee Champion, a doctoral student in the Department of Aerospace Engineering Sciences at the University of Colorado Boulder, told Live Science.
avoid disaster
The tractor beams depicted in “Star Wars” and “Star Trek” suck spaceships through artificial gravity or vague “energy fields.” Such technology is probably beyond what humans can achieve. But the concept inspired Hanspeter Schaub, a professor of aerospace engineering at UW Boulder, to envision a more realistic version.
Schaub first came up with the idea after the first major satellite collision in 2009. The active communications satellite Iridium 33 collided with the Russian military spacecraft Cosmos 2251, sending more than 1,800 pieces of debris into Earth’s orbit.
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In the wake of this disaster, Schaub wanted to prevent something like this from happening again. To do this, he realized that he could use the gravitational force between positively and negatively charged objects to “stick” them together, thus moving the spaceship out of harm’s way.
Over the next decade, Schaub and colleagues refined the concept. Now, they hope they can one day use the satellite to move it out of geostationary orbit (GEO). A GEO is an orbit around the Earth’s equator in which the object’s speed matches the rotation of the planet and the object appears to be fixed over a particular point on the Earth. This will free up space for other objects within GEO, which is considered “prime real estate” for the satellite, Schaub said.
How does it work?
Champion said the electrostatic tractor would use a servicer spacecraft equipped with an electron gun that fires negatively charged electrons at dead target satellites. The electrons give the target a negative charge and leave the servicer with a positive charge. The electrostatic attraction between them keeps them fixed to each other even when separated by 20 to 30 meters (65 to 100 feet) of empty space.
Once the servicer and target are “stuck,” the servicer can drag the target out of orbit without touching the target. Ideally, the defunct satellites would be pulled into a “graveyard orbit” farther from Earth, where they could safely drift forever, Champion said.
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The electrostatic attraction between the two spacecraft would be very weak because of the limitations of electron gun technology and the distance the two spacecraft would need to be separated to prevent a collision, project researcher Julian Hammar, a doctoral student at UW Boulder, told Live Science. As a result, servicers have to move very slowly, and it can take more than a month to completely move one satellite out of GEO, he added.
It’s very different from the movie tractor beam, which cannot escape and quickly engulfs its prey. This is “the main difference between science fiction and reality,” Hamerle says.
Advantages and limitations
Electrostatic tractors have one major advantage over other proposed space debris removal methods, including harpoons, giant nets, and physical docking systems. It’s completely touchless.
“It’s a big, dead spaceship, about the size of a school bus, spinning around really fast,” Hammerle said. “If you shoot a harpoon, use a large net, or try to dock with a spacecraft, you can damage the spacecraft through physical contact, and in that case you’ll just damage the spacecraft. [space junk] The problem is even more serious. ”
Scientists have suggested other contactless methods, such as using powerful magnets, but large magnets are expensive to manufacture and are likely to interfere with servicer controls, Champion said.
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The main limitation of electrostatic tractors is that they operate slowly. GEO currently has more than 550 satellites orbiting the Earth, and that number is expected to grow rapidly in the coming decades.
By moving satellites one at a time, a single electrostatic tractor cannot keep up with the number of satellites that can go out of service in the blink of an eye. Another limitation of electrostatic tractors is that they cannot completely remove debris from GEO because they operate too slowly to be practical for removing small space debris.
Another major hurdle is cost. Schaub said the team has not yet done a full cost analysis of the electrostatic tractor, but it will likely cost tens of millions of dollars. But he added that if servicers went to space, they could operate relatively cost-effectively.
next step
The researchers are currently working on a series of experiments at the Electrostatic Charge Laboratory for Plasma-Spacecraft Interactions (ECLIPS) at UW Boulder. A metal vacuum chamber the size of a bathtub equipped with an electron gun will allow the research team to “perform unique experiments that almost no one is currently able to do” to simulate the effects of electrostatic tractors on a smaller scale, Hammerle said.
Once the team is ready, the final and most difficult hurdle is securing funding for the first mission, a process the team has not yet begun.
Most of the mission cost comes from building and starting the servicer. But researchers ideally want to launch two satellites, a servicer and a steerable target, for initial testing. That gives you more control over your experiments, but it also doubles the cost.
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The researchers previously estimated that if they could somehow find the funding, a prototype tractor beam could be ready for use within about 10 years.
Is it doable?
Tractor beams may sound like a pipe dream, but experts are optimistic about the technology.
“Their technology is still in its infancy,” John Clasidis, an aerospace scientist at the University at Buffalo in New York who was not involved in the study, told Live Science in an email. “But I’m pretty confident it will work.”
Shooting a harpoon, using a large net, or attempting to dock with a harpoon can damage your spaceship through physical contact, in which case you will simply damage it. [space junk] The problem gets worse.
Removing space junk without touching it is much safer than current alternatives, Krasidis added.
Carolyn Frew, an associate professor of aerospace at Purdue University in Indiana, told Live Science in an email that an electrostatic tractor “should be able to generate the force necessary to move a defunct satellite,” and that it “certainly has a good chance of practical application.” “However, there are still some engineering challenges to be solved before it can be used in the real world.”
Scientists need to continue researching other possible solutions, Krasidis said. He added that even if the CU Boulder team doesn’t create a “final product” to remove defunct satellites, their work could be a stepping stone for other scientists.
If the research is successful, it will not be the first time scientists have turned fiction into reality.
“Today’s science fiction can become tomorrow’s reality,” Krasidis said.
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